Color Change of Selected Wood Species Affected by Thermal Treatment and Sanding

Optimal cutting conditions, which lead to a high quality of the machined surface and low energy consumption, are crucial for wood processing. This paper describes the effect of feed speed, cutting speed and mean chip thickness on energy consumption and saw blade surface temperature during the spruce (Picea excelsa) cutting process. In the experiment, the energy consumption and the surface temperature of the saw blades were measured to find the optimal cutting conditions for the energy-efficient cutting process. The surface temperature of the circular saw blade was monitored online using a non-contact infrared sensor connected directly to a PC via a USB connector. The results show that the cutting power and the surface temperature of the circular saw blade increased with increasing feed speed. The lowest values of cutting power were shown by the saw blade CSB3. Compared to the classic CSB1 circular saw blade, the values were lower by 8%. The surface temperature of the circular saw blade is highest at the outer edge (area of the heel of the teeth), and decreases towards the center of the circular saw blade. For an identical mean chip thickness, energy-efficient cutting was achieved at a feed speed of 21 m/min. There must be a trade-off between machine productivity and energy consumption. Monitoring the cutting process of circular saws using intelligent sensors is the way to adaptive control systems that ensure higher quality of the machined surface and cost-effective machining.

Milling with use of CNC machines is a well-established method and much research was concluded on this topic. However, when it comes to wood and wood composites, the material non-homogeneity brings a lot of variability into cutting conditions. As a part of research into potential signals for nesting milling, material vibrations at clamping points were examined in this study. The main goal was to conclude if cutting parameters have a statistically significant effect on measurement. The place of measurement was analyzed so it was accessible to the machine operator. Medium density fiberboard and particleboard specimens were cut through by razor and spiral mill, with spindle rotating 10,000 and 20,000 min⁻¹ and feed rates 2, 6, 10 m·min⁻¹. Vibrations were measured at vacuum grippers, and were then processed by fast Fourier transform. Then, frequency spectrum maxima were compared, as well as amplitude sizes. Main frequencies were of roughly 166 Hz and multiples, suggesting their origin in tool rotation. When maxima were compared, tool use, spindle rotation, and feed rate seemed to affect the result. Frequency spectrum amplitudes were subjected to analysis of variance, significant effect was found on spindle speed, tool, and specimen material. No significant effect was found with differing feed rates.

The impact of technical and technological parameters on the quality of machining during milling of thermally modified pine wood (Pinus sylvestris L.) was studied. Experiments were conducted to evaluate the effects of tools (α = 30°, β = 45°, γ = 15°, 20°, and 30°), material (natural material, thermally treated at 160 °C, 180 °C, 210 °C, and 240 °C), and technological factors, such as cutting speed (20 m.min-1, 40 m.min-1, and 60 m.min-1) and feed rate (6 m.min-1, 10 m.min-1, and 15 m·min-1) on the quality of the machined surface (standard deviation of surface Ra). The roughness measurements were realized by a non-contact method using a laser. This paper aimed to highlight which one of the technological or tool factors had the greatest impact on the quality of the surface of heat-treated wood in face milling. The importance of the parameters impact on surface quality was in the following order: rake angle, feed rate, thermal treatment, and cutting speed.

The aim of the paper is to present the concept of a digital twin (DT) as part of the Industry 4.0 strategy. In the form of a case study, a digital twin of a production line for the processing of engine blocks is presented, which will serve as a starting point for further research in the field of digitization of production processes. The research part describes the simulation model of the production line with the representation of the material flow as a basis for the creation of a digital twin. The simulation model was used to optimize the production processes of the engine block and to verify the increase in its productivity. A case study implemented through a digital twin enables testing and analysis of changes before they are introduced into real production.